How To

”rsync” is an open source utility in Linux/Unix primarily used for synchronising files/directories over the networks. You can also use it to backup/copy folders between machines. It is particularly made use of to while administering servers connected to the internet. The term “rsync” itself refers to “remote-synchronise”.

On a WHM/cpanel VPS server the httpd.conf is automatically generated from cpanel scripts based on templates and you are not supposed to change this file directly. Any changes that you make in the httpd.conf file will be lost when cpanel re-generates the file or when cpanel is updated. This is an inconvenience especially when your application requires you to make virtualhost modifications in the configuration. However cpanel provides an alternative way to edit the httpd.conf file.

When you untar large tar files even as the root user on your VPS you might run into the error "Cannot change ownership to uid NNN, gid NNN: Disk quota exceeded". This is because the extracted files from the tar archive is being attempted to be created with the original UID and GID as on the system where the tar archive was created. Now if the UID is not already present on the new VPS or if the UID corresponds to a user without a lot of disc quota available the above error will be triggered preventing extraction of the tar.gz archive.

Most of us must be familiar with the names 'dig' and 'whois'. If not, these are two commands used to find the details of domains. You just have to type in dig domainname or whois domainname to get a comprehensive set of info on the domain. What if you have not just one or two domains to check about. How about a 1000 domains and you want to know the details of each?

Redmine is one of the most popular Ruby on Rails applications which has made quite a name for itself in the world of Project Management. It offers a lot of flexibility. One of its main advantages is that it can recognize your files repository and can work along with your source control system to keep track of all changes through the tracker itself. Here is one error that we came across when we tried to integrate our filesystem and source control management system with Redmine - Error: The entry or revision was not found in the repository

Some times we wish to exclude some files and directories when we try to take backup of a website. With tar it is possible. Use the --exclude option. For example, if you want to exclude .git folder and the imagecache directory inside the files folder, use the command: tar -zcvf abc.com.tar.gz --exclude ".git/*" --exclude ".git" --exclude "sites/default/files/imagecache/*" --exclude "sites/default/files/imagecache" public_html

Some of the latest Laptops especially Dell Inspiron 5420 and Lenovo G580 series comes with Atheros Network driver which has some problem with Ubuntu 12.04. The problem is that it will not detect the wired network connection(eth0) even though wireless connection is working fine. We can solve this issue by installing the proper network driver.

Generating SSH keys and using them for connecting to SSH servers is a straightforward process on Linux. But for Windows users, Windows does not provide any support for the SSH protocol by default. There is no SSH client that comes by default on Windows. Let alone generating keys.

Unlike proprietary operating systems that comes up with a rudimentary set of applications, Ubuntu and GNU/Linux in general has thousands of freely available Free Software applications available for installation directly from the Internet. These applications are usually available from software archives referred to as repositories. The official Ubuntu repositories contain more than 30000 applications. Having the Ubuntu repositories on DVD can be useful for those users who don't have access to the Internet or has only limited connectivity from the machine where they have their Ubuntu installed but have access from somewhere else to download the repository. Here is a step by step instruction on how to download the complete Ubuntu repositories and build your own set of Ubuntu Repository DVDs. For those who would like to get it done the easy way you can buy a set of Ubuntu Repository DVDs via our RequestCD program

Ubuntu 12.04 comes with a bug that it will not mount the cdrom on proper path and that prevents installation of applications from the Ubuntu Repositories even if you add the repositories via apt-cdrom successfully. Whenever you try to install applications you'll get an error message like E: Unable to stat the mount point /media/cdrom/ - stat (2: No such file or directory) Here is how to fix this problem:

As the world of internet grows day to day, the more educated and ever-wanting userbase now needs more data asynchronously. They don’t like to wait or load another page to see their data. In such situations we developers need to use more and more AJAX (Asynchronous JavaScript and XML - http://en.wikipedia.org/wiki/Ajax_(programming)) in the development of websites. Using AJAX in your web-development workflow is not that much difficult as you think. There is already a wide range of famous ajax libraries that make handling asynchronous requests easy for us.

Apache allows you to protect contents of specific directories in your website or the whole website from unauthorized access using a mechanism called httpd password protection. During development of new sites the partially built sites are protected from unauthorized access using httpd authentication. This could sometimes interfere with testing of integration with third party services that might expect some of your URLs to be accessible without authentication. Here is how you can exclude a given file or directory from httpd authentication